Burglar alarm system



April 16, 1968 SHU-LIEN LIOU BURGLAR ALARM SYSTEM Filed Aug. 16, 1965 RO m V m JHU-L/f/V A /00 United States Patent 3,378,832 BURGLAR ALARMSYSTEM Shu-Lien Liou, 195 Sec. 3, Chungkiug Road N., Taipei, TaiwanFiled Aug. 16, 1965, Ser. No. 480,075 13 Claims. (Cl. 340-274) Thisinvention relates to alarm devices for indicating unplanned orunauthorized actions including burglar alarm systems.

The invention relates particularly to a device which can indicateunauthorized operation of a mechanism. For example, it will set off analarm signal if a lock is opened by anyone who does not first arrangeassociated elements in a predetermined position.

While locks do much to prevent theft, there are some particularly brazenthieves who have the skill or the equipment to unobtrusively open locks.Some have sets of skeleton keys. Others know techniques for pickinglocks, or other methods of opening them without keys. Some can opencombination locks by particular manipulations. Pickpockets have beenknown to deliberately steal keys to a desired lock. Persons who knowsuch techniques are also likely to have the intelligence and the skillto open locks without attracting public attention. They may be welldressed and nothing about them may suggest thatthey are thieves.

Unauthorized lock operation triggers an alarm bell under this invention.A tape recorder shouting Stop thief! or some similar message may beincluded.

Alarm systems actuated by unauthorized atempts to use locks were knownin the days of Queen Elizabeth in the sixteenth century, and many havebeen suggested since that time. However, they do not appear to haveachieved widespread use, perhaps because they were overly expensive,unreliable, or too easy to circumvent.

The invention is also useful to indicate unauthorized use of machinery.For example, it can attract attention to unauthorized use of anautomobile. The invention might also be applied to industrial machinerywhich might be damaged by unqualified employees. The embarrassment ofsetting off a bell that attracts the attention of a whole factory canteach such an employee a lesson that might save his life.

A major object of this invention is the provision of a device toindicate unauthorized use of mechanisms including locks invarious typesof machinery.

A further object is to provide such a device which is cheap tomanufacture, reliable in operation, simply operated, and small in sizeso that the presence of the device is not apparent to those who plansuch unauthorized use.

Briefly stated the invention consists of an alarm system which isactivated by use of a mechanism, for example, by opening a lock with akey, unless the operation of the alarm system is circumvented. Operationof a concealed device is necessary to circumvent the alarm system. Theconcealed device may be similar to a combination lock and can only beoperated by a person who knows the proper combination to manipulate thedial to the off position.

In one embodiment of the invention applicant mounts a small spring sothat it will move with a link in a door latch mechanism as the door isopened after unlocking. This spring has a projection that moves into anotch formed in the sides of a number of concentric disks of equal size.By operation of a dial similar to that of a combination lock, thenotches in the individual disks are brought into alignment to form anopening to receive the straight projection. If this opening is notformed movement of the door latch carries the projection against3,378,832 Patented Apr. 16, 1968 "ice the side of the disks, and furthermovement of the projection closes electrical contacts to activate analarm system.

Other objects and advantages of the invention will be apparent from thefollowing drawings in which:

FIG. 1 is a plan view, partly schematic of a portion of a door latchingand locking mechanism utilizing the present invention;

FIG. 2, a perspective view of a spring member utilized with thestructure of FIG. 1;

FIG. 3, a plan view illustrating another embodiment of the invention;

FIG. 4, a side view of the structure of FIG. 3 showing the mechanism ofFIG. 3 with the mechanism for actuating a burglar alarm in theinoperative position;

FIG. 5, a side view of the structure of FIG. 3 showing the mechanism ofFIG. 3 with the mechanism for actuating a burglar alarm in the operativeposition; and

FIG. 6, a perspective view of a spring member used in the mechanism ofFIG. 3.

With further reference to FIG. 1 of the drawings, a movable member 10 ofa door latch mechanism 11 includes arm 12 normally blocked in lockedposition by a bolt 14 of a lock mechanism 15. Movable member 10 may beany part whatever that moves when a door is opened after it is unlocked.Movable member 10 also has an arm 13 with a projecting part thereonblocked in locked position by a combination dial lock 18 comprising anumber of separate disks 19 each of which has a notch 20 cut therein. Ifnotches 20 are aligned and bolt 14- is moved out of locking positionmovable member 10 can move to the right by moving the projecting partinto the large opening formed when the three smaller notches 20 of theindividual disks 19 are brought into alignment.

A bracket 23 secured to movable member 10 has a fiat rectangular metalspring member 25 secured to it by rivet 28 and spacer 29. Spring member25 has a central strip 26 cut out and bent first away from the arm 23and toward combination lock 15 and then back through the central opening27 of the spring member 25. The bottom of central strip 26 is mounted ina groove 33 in a bar 31 and biases it against the bottom of slots 34 and35 cut in front wall 36 and rear wall 37 of bracket 23. Bar 31 extendsthrough the opening 27 of spring member 25 and has a wider part 32 atone end.

A combination mechanism 40 has a number of disks 41 each with a notch 42cut therein. When notches 42 are brought into alignment they form alarger opening in which wider portion 32 of bar 31 can move when lock 15and combination lock 18 are unlocked. However, if notches 42 are notaligned wider portion 32 of bar 31 strikes the side of combinationmechanism 40 as movable member 10 travels to the right. Front wall 36 ofbracket 23 carries an electrical contact 45 separated from it byinsulator 46. Spring member 25 also carries an electrical contact 47. Anelectrical circuit 50 joins these electrical contacts through powersource 51, audible alarm 52, a tape recorder 53, and the intermediatestructure.

The operation of the device of FIG. 1 is as follows: Normally the dooris kept locked "by bolt 14 and combination lock 15 and electric contacts45 and 47 are normally spaced from each other by a distance which isgreater than the distance between either arm 12 and bolt 14 or arm -13and combination lock 18. Accordingly, the electrical contacts are notmoved to engaging position by moving member 10 slightly while locked.Accordingly, persons testing the door to see whether it is locked orchildren playing would not normally set off the alarm.

However, if an unauthorized person who manages to move bolt 14 out ofthe way as by picking the lock or obtaining the key without authorityand if he is further able to manipulate combination lock 18 to openposition must move latch member 10 to the right to open the door.However, member 10 carries bar 31 with it and when wider portion 32strikes the edge of combination mechanism 40 spring member 25 bends tothe right as a reaction to the movement of bar 31 to the left. Thiscloses the electric contact to ring the bell. Any type of bell or anyother alarm signal desired can be used. If desired a tape recorder canalso be connected to call out Stop thief! or other messages such as Aburglar alarm has been actuated! Please call the police.

FIGS. 3 to 6 illustrate an alternative form of the invention. A pair oflatch mechanism members 110 and 111 each have notches 112 cut therein.These notches can be brought into alignment to form a larger opening byany appropriate mechanism. When a door is opened latch members 110 and11 1 move in the vertical direction as shown in FIGS. 3, 4, and towardan alarm actuating mechanism 115. Actuating mechanism 115 includesspring holder 120 having a front wall 121 and a rear wall 122 joined byside wall 123. An offset portion of the front wall 121 carries anelectrical contact 125 which is insulated therefrom. A spring member 130is slidably mounted between front wall 121 and rear wall 122. Springmember 1130 consists of a long flat strip of metal bent into a generallyU shape. One leg 131 of the U is formed by portions 132 and 133 bentupon themselves. The other leg 134 consists of portion 135 of the strip.Legs 131 and 134 are joined by center projection 138 consisting ofportion 139 which is bent outwardly from portion 133, portion 140 bentinwardly to extend post leg 131, and portion 141 bent back toward leg131 and which joins leg 134. The springiness of the metal tends to keepthe legs well spread. Spring 1330 is normally mounted in spring holder120 with portions 139 and 141 of projection 138 spaced from front wall121 and rear wall 122. An electrical contact 143 on leg 134 engageselectrical con tact 125 if spring 130 is pushed further into springholder 120. Wires 146 and 147 of the alarm circuit join electricalcontacts 143 and 135.

The device of FIGS. 3 to 6 operates as follows: spring member 130 isnormally retained between the front and rear walls 121 and 122 withprojection 138 in an extended position as illustrated in FIG. 3. Thedoor is unlocked and notches 1-12 of latch members 110 and 111 are movedinto alignment. Latch members 110 and 111 are moved toward mechanism115' and projection 138 moves into the opening formed by notches 112. Noelectric circuit is closed and the alarm does not ring. On the otherhand, if the latch members 110 and 111 are moved toward the alarmmechanism without aligning the notches: (1) members 110 and 111 strikethe projection 138; (2) spring member 130 moves further into holder 120;(3) spring leg 134 and electrical contact 143 move and engage the otherelectrical contact 125; and (4) the alarm circuit is actuated.

It will be readily apparent that a device has been provided which issimple in structure, reliable in operation, and economical tomanufacture. This device will actuate an alarm if the lock mechanism orany other mechanism is operated without first arranging certain elementsin a predetermined position.

It will be obvious to one skilled in the art that various changes may bemade in the invention without departing from the spirit and scopethereof, and, therefore, the invention is not limited by that which isillustrated in the drawings and described in the specification, but onlyas indicated in the accompanying claims.

What is claimed is:

1. A device for indicating unauthorized operation of a mechanism havingrelatively movable members comprising,

(A) a first member having (1) a first part mounted thereon,

(2) a second part mounted for movement relative to the first part,

(B) a second member (1) mounted for movement relative to the firstmember,

(2) means to selectively provide an opening in the second member of anappropriate size and shape to receive the second part of the said firstmember during operation of the mechanism, and,

(3) means to move the said second part of the first member relative tothe first part as the first member moves toward the second member attimes when said means for forming an opening are not actuated,

(C) an alarm signal means, and,

' (D) means to activate said alarm signal means when relative movementoccurs between the first part and the second part of the first member.

2. The structure of claim 1 in which said second member is an assemblyof relatively movable parts each having an indentation therein, and themeans for providing an opening comprises means to relatively move saidparts so that the indentations are aligned.

3. A device for indicating unauthorized attempts to operate a mechanismcomprising,

(A) a mechanism,

(B) a support connected to the mechanism,

(C) a first member on the support,

(D) a second member on the support,

(E) means on the support to cause relative movement of the said firstmember toward the second member when said mechanism is operated,

(F) said first member having means to selectively provide an opening inits side,

(G) said second member having (1) a fixed part having (a) spaced sidemembers defining an opening therebetween extending in the direction ofrelative movement between the first and second members,

(b) an offset portion fixed to one side member and carrying anelectrical contact located on the side of the opening opposite the saidfirst member,

(2) a generally U-shaped spring metal member (a) slidably mounted withinthe opening in the fixed part,

(b) one leg of the U carrying an electrical contact so located so thatit can engage the electrical contact on the offset portion of the saidfixed part in response to sliding movement of the U within the saidopening,

(c) having the portion joining the legs of the U extending from the sideof the opening and forming a projection so located that it can move intothe said opening in the side of the first member,

(H) an alarm signal means, and

(I) means to activate said alarm signal means when said projection movestoward said fixed part on the second member.

4. A device for indicating unauthorized attempts to operate a mechanismcomprising,

(A) a mechanism,

(B) a support connected to the mechanism,

(C) a first member on the support,

(D) a second member on the support,

(E) means on the support to cause relative movement of the said firstmember toward the second member when said mechanism is operated,

(F) said first member having means to selectively form an opening in itsside,

(G) said second member having (1) a fixed part carrying an electricalcontact thereon and (2) an elongated springy sheet metal member (a)having an electrical contact on one end (b) secured to the fixed part atits opposite end at a position such that ilexure of the elongatedspringly sheet metal member will bring its electrical contact intoengagement with the electrical contact of the fixed part,

(c) an elongated strip out within the central portion and bent to curveaway from the member on the side opposite the fixed part at its endnearest its electrical contact, said strip being then bent to curve backin toward the said member,

(3) a movable rod (a) mounted within the opening in the spring metalmember and (b) engaging the end of the elongated strip of the springmetal member,

(c) said rod so located that it will engage the side of the first memberand cause the spring metal member to flex and bring the electricalcontacts into engagement as the second member moves relatively to thefirst unless said opening has been made in the side of the first member,

(H) an alarm signal means, and

(I) means to activate said alarm signal means when said projection movestoward said fixed part on the second member.

5. A device for indicating unauthorized operation of a mechanism havingrelatively movable members comprising (A) a first member having (1) afirst part mounted thereon,

(2) a second part associated with said first part and means mounting thesecond part for movement relative to the said first part,

(B) a second member (1) mounted for movement relative to the firstmember, and

(2) having selectively actuated means for causing relative movementbetween first and second parts during relative movement of said firstand second members during operation of the mechanism,

(C) an alarm signal means, and (D) means to activate said alarm signalmeans in response to relative movement of the said first and secondparts. 6. The structure of claim 5 in which said mechanism is a lockmechanism.

7. The structure of claim 5 in which said mechanism is a lock mechanismactuated by a key.

8. The structure of claim 5 in which said first part and said secondpart are electrical contacts and the means to activate the alarm systemincludes an electrical circuit joining the said electrical contacts.

9. The structure of claim 5 in which said alarm means produces anaudible signal.

10. The structure of claim 5 in which said alarm means includes a taperecorder.

11. The structure of claim 5 in which said alarm system includes a bell.

12. The structure of claim 5 in which said second part includes a metalspring.

13. The structure of claim 5 in which the movable mounting for saidsecond part includes a metal leaf spring carrying an electrical contact,and said first part also includes an electrical contact positioned sothat relative movement between the said parts brings the electricalcontacts into engagement, and the means to activate the alarm systemincludes an electrical circuit adjoining the said electrical contacts.

References Cited UNITED STATES PATENTS 1,424,298 8/19 2 Gifford ZOO-1,708,279 4/ 1929 Milliken 200-45 2,003,650 6/1935 Hosking.

JOHN W. CALDWELL, Primary Examiner.

D-. L. TRAFTON, Assistant Examiner.

1. A DEVICE FOR INDICATING UNAUTHORIZED OPERATION OF A MECHANISM HAVINGRELATIVELY MOVABLE MEMBERS COMPRISING, (A) A FIRST MEMBER HAVING (1) AFIRST MEMBER HAVING (2) A SECOND PART MOUNTED FOR MOVEMENT RELATIVE TOTHE FIRST PART, (B) A SECOND MEMBER (1) MOUNTED FOR MOVEMENT RELATIVE TOTHE FIRST (2) MEANS TO SELECTIVELY PROVIDE AN OPENING IN (2) MEANS TOSELECTIVELY PROVIDE AN OPENING IN THE SECOND MEMBER OF AN APPROPRIATESIZE AND SHAPE TO RECEIVE THE SECOND PART OF THE SAID FIRST MEMBERDURING OPERATION OF THE MECHANISM, AND,